This invention relates to the general field of exfoliative cytology, which includes such well-known procedures as the cervical "pap test," gastric, esophageal, and bronchial brush cytology, and peritoneal and pleural fluid cytology. The field also includes renal, ureteral cytology, hepaticobiliary cytology.
These procedures have previously been limited by the fact that the cell-collecting methods and instruments have been too large (a minimum of 1 mm in diameter). This limitation has prevented early diagnosis of the presence of malignant cells in remote ductal areas such as the pancreatic duct, where a very substantial number of malignancies occur.